In order to gain access to specific inner areas of the body, often times elongated, flexible guide units are used to enter the body through a small opening and travel through parts of the body through convenient channels. Guide units may be passed into the body via peripheral blood vessels, the gastrointestinal tract, or the urinary tract. Guide units, often referred to as guide wires, are commercially available and are currently used in cardiology, gastroenterology, urology, and radiology. Guide wires, once in place, serve as guides for the introduction of additional medical instruments such as catheters.
To assist in threading a guide through a predetermined body channel such as an artery, the guide may include a generally flexible body portion which is resistant to kinking and a forward end portion of increased flexibility, the end portion terminating in a smoothly rounded tip. The body portion may include a core of stainless steel or other metal, the core being appropriately dimensioned in cross section to provide the desired degree of flexibility to the guide wire. A coating of plastic, a plastic tube, or the like may be applied over the surface of the core, if desired. In order to provide greater flexibility to the guide at its forward end, the forward end of the core may include a section of lesser diameter and hence, of greater flexibility. An elongated, flexible helically wound wire forming an elongated coil may be employed at the forward end of the guide wire and may extend throughout the length of the guide wire. The coil functions to make the guide wire tip flexible to facilitate the tip in being guided through body channels. A small plug, preferably integrally formed on the forward end of the core, provides an attachment for the wire coil. The core may terminate at a position spaced from the guide end to provide the guide end with increased flexibility.
Safety wires are commonly employed with guide wires to prevent the forward end of the guide from unintentionally becoming detached from the body of the guide wire when the guide is removed from a body channel. In some cases, the core provides the function of a safety wire.